Fog and other aerosols such as dust have caused serious problems in the area of navigation for land, air, and sea navigation. In the case of aircraft, it is the landing of the aircraft that is the crux of the problem. If the pilot could see well enough through the fog and other aerosols to determine the runway and any obstacles, he could land his aircraft. The best current system that is used is radar that transmits well through fog and other aerosols but does not have enough spatial resolution to allow pilots to land their aircraft safely.
One prior art method for "seeing through fog and other aerosols" is described in U.S. Pat. No. 4,670,637. In this method, a laser signal is directed into the fog is amplitude modulated at one of the resonant frequencies of the water droplets forming the fog at such strength as to cause the droplets having this resonant frequency to burst, thereby decreasing the scattering of the laser signal and increasing the transmission of this signal through the fog. This system, of course, does not strictly enable "seeing through fog and other aerosols" but merely aids in the transmitting of laser signals through the fog and provides a method for transmitting laser signals through fog which requires less power than if the fog had not been somewhat dissipated.
Another prior art method for "seeing through fog and other aerosols" is described in U.S. Pat. No. 4,920,412. The system includes a television camera or an optical viewer device with a gated image intensifier input. A short intense laser pulse is transmitted to illuminate the scene. The image intensifier is gated on after a time delay equal to the round trip transit time of the pulse from a range slice of interest. The image intensifier is gated on for a time interval equal to the width of the laser pulse. In the television camera embodiment, one laser pulse per frame is transmitted and successive range slices are observed during successive frames by successively increasing the time delay. The range slice images are stored in a buffer and read out to a television display. In the optical viewer device embodiment, a segmented horizontally sliced electro-optical shutter is disposed adjacent the phosphor output of the image intensifier to transmit successive range slice information to an eyepiece of the device for viewing by an observer. The optical viewer device may be mounted on a helmet with an inclinometer on the helmet providing signals to program the segmented shutter. This method does not provide any deblurring of the reflected laser radiation that produces forward scattering blur on its way back to the airplane pilot's camera.
The closest related area that has been used is that of ground vehicle navigation in fog. Yellow light headlights are used to illuminate the highway from a position close to the ground. This penetrates the fog where our human vision is most sensitive and from a position that reduces the impact of backscatter but does not utilize the benefits that can be obtained from wide baseline (hyperstereo) stereo imaging. There is currently no counterpart for aircraft.